THIWASCO tariff explained (Kenya 2026)

Every water bill in Kenya is a stack of at least four line items: water charge (block tariff on volume used), sewer charge (percentage surcharge if connected), fixed standing or meter charge, and any statutory levies (WSTF cess and, on some commercial classes, VAT). THIWASCO follows this standard structure with rates set by WASREB.

Domestic tariff bands

Domestic accounts pay a block tariff that increases as monthly consumption climbs. The first block is a subsidised lifeline meant to keep 6 m³ per month (roughly the WHO basic-needs threshold for a household of four) affordable.

Commercial and institutional tariff

Commercial, industrial and institutional accounts pay flat higher rates without the lifeline subsidy. Typical range is KES 130 to KES 220 per m³ depending on the WASREB-approved class. Schools and hospitals sometimes have preferential institutional rates. Ask THIWASCO customer care for the exact schedule for your class.

Sewer surcharge

If your property is connected to the THIWASCO sewer network, a sewer charge of approximately 70 percent of your water charge is added to the bill. The regulator justifies the percentage-of-water approach as a proxy for sewerage volume, which is more expensive to meter directly. If you are on a septic tank or pit latrine, no sewer charge should appear. Contest any sewer line item on a septic property in writing.

Standing / meter charge

A fixed monthly charge of approximately KES 150 covers meter rental, meter reading, billing administration and account maintenance. It applies whether you used water or not, which is why a vacant property still gets a small bill each month.

Statutory levies

• Water Resources Regulatory Levy (WRA) and Water Services Regulatory Levy (WASREB): small per-cubic-metre contributions passed through to fund the regulators. Typically KES 0.50 per m³ combined. Line item labelled "WSTF cess" or "regulatory levy".
• VAT: piped domestic water is VAT-exempt in Kenya. Sewerage and some commercial supplies can attract 16 percent VAT depending on the class.

Worked example

A household using 18 m³ in a month with sewer connection, on THIWASCO:

• 6 m³ at KES 55.00 = KES 330
• 12 m³ at KES 85.00 = KES 1020
• Water subtotal = KES 1350
• Sewer at 70 percent = KES 945
• Standing charge = KES 150
• Estimated total = KES 2445

Run your own numbers on the THIWASCO bill calculator.

How tariffs get changed

WASREB approves new tariffs through a public-consultation process. THIWASCO submits a proposal, WASREB publishes it, consumers submit comments through a public hearing, and WASREB issues a determination. Most Kenyan WSPs seek review every 3 to 5 years. Watch the WASREB notices page for the current cycle.

Disputing a tariff line

If you believe a rate has been misapplied (wrong tariff class, sewer on a septic property, arrears carried incorrectly), write to THIWASCO customer service with the bill copy, your evidence and a clear ask. Escalation path:

1. THIWASCO customer care: 0709 999 100
2. THIWASCO written complaint at THIWASCO offices, Kenyatta Highway, Thika
3. WASREB consumer complaint portal (wasreb.go.ke)

Sources

• WASREB tariff register, wasreb.go.ke/my-tariffs, accessed 26 August 2026.
• THIWASCO website, thiwasco.co.ke, accessed 26 August 2026.
• WASREB Impact Report 17 (published 2025), utility performance benchmarks.